In steel mill operations, large ladles and like vessels are periodically charged with molten metal which is withdrawn through a well or hole formed through the thick bottom of the ladle. Such ladles are conventionally lined with a refractory material. See for example, U. S. Pat. No. 4,368,834 to Daussan et al, entitled: Preheating Device For Stopper-Type Tundishes; U.S. Pat. No. 3,944,116 to Danieli, entitled: Process And Device For Aiding In Opening The Tundish Nozzle In A Continuous Casting System; U.S. Pat. No. 3,511,261 to Bick et al, entitled: Controllable Teeming Valve For Steel-Casting Ladles; U.S. Pat. No. 4,037,762 to Ruckstuhl, entitled: Protective Nozzle For The Outlet Of A Casting Ladle; and U.S. Pat. No. 3,197,824 to Dolenic et al, entitled: Nozzle Block For Ladles.
As can be seen from several of these references and also from U.S. Pat. No. 4,116,421 to Rowe, entitled: Method Of Sealing Tapholes In A Phosphorus Furnace, it is considered desirable to block or plug up the well so that the molten metal may not immediately flow into it. This is done so that the metal will not harden in the well (cold steel splashes) nor slag pieces become wedged therein. It is also done to lessen thermal shock to the well sides. Such thermal shock may lessen the useful life of the refractory lining of the well. Commonly, the well is blocked or plugged with refractory sand, chrome sand or granular quartz, all which we will here call "sand". To prevent such sand from being blown or splashed out during preheating or upon the initial charging of the vessel, a disposable cover is sometimes placed over the sand in the well.
This sand and cover were heretofore placed into and over the well by having a workman go into the ladle (often in a cage suspended from a crane). The workman would then place the sand and cap by hand in and over the well. Now, for overall efficiency in mill operations and for energy-saving reasons, it is desirable to fill the ladle as often as possible and to keep it and its refractory lining at a high temperature. Thus, the job of so charging the well and placing a cap or cover must normally be done quickly in extremely hot and dangerous conditions. Yet, because the sand used is relatively expensive and proper placement considered of such importance, this dangerous and uncomfortable method of accomplishing this end had become the accepted practice.